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Jean-marie Flament - One of the best experts on this subject based on the ideXlab platform.
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The tectono-sedimentary evolution of a hyper-extended rift basin: the example of the Arzacq–Mauléon rift system (Western Pyrenees, SW France)
International Journal of Earth Sciences, 2014Co-Authors: Emmanuel Masini, Geoffroy Mohn, Gianreto Manatschal, Julie Tugend, Jean-marie FlamentAbstract:In this paper, we present a sedimentary and structural analysis that together with maps, sections and new Ar/Ar data enable to describe the tectono-sedimentary evolution of the Mauléon hyper-extended rift basin exposed in the W-Pyrenees. Hyper-extension processes that ultimately resulted in exhuming mantle rocks are the result of the subsequent development of two diachronous detachment systems related to two evolutional stages of rifting. An initial Late Aptian Early Albian crustal thinning phase is first recorded by the development of a crustal Necking Zone controlled by the north-vergent Southern Mauléon Detachment system. During a subsequent exhumation phase, active faulting migrates to the north with the emplacement of the Northern Mauléon detachment system that exhumed north section thinned continental crust and mantle rocks. This diachronous crustal thinning and exhumation processes are also recorded by the diachronous deposition of syn-tectonic sedimentary tracts above the two supra-detachment sub-basins. Syn-tectonic sedimentary tracts record the progressive exhumation of footwall rocks along detachment systems. Tectonic migration from the southern to the northern Mauléon Detachment system is recorded by the coeval deposition of “sag” deposits above the Necking Zone basin and of syn-tectonic tracts above exhumed rocks north section. Located on a hanging-wall situation related to the Mauléon hyper-extension structures, the Arzacq Basin also records a major crustal thinning phase as shown by its subsidence evolution so as by deep seismic images. The absence of major top-basement structures and its overall sag morphology suggest that crustal thinning processes occurred by decoupled extension of lower crustal levels contrasting with the Southern Mauléon Detachment system. Reconciling observations from the Mauléon and Arzacq Basins, we finally propose in this paper that they were the result of one and the same asymmetric crustal thinning and exhumation processes, where extension is accommodated into the upper crust in the Mauléon Basin (lower plate basin) and relayed in ductile lower crust below the Arzacq Basin (upper plate basin).
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the tectono sedimentary evolution of a hyper extended rift basin the example of the arzacq mauleon rift system western pyrenees sw france
International Journal of Earth Sciences, 2014Co-Authors: Emmanuel Masini, Geoffroy Mohn, Gianreto Manatschal, Julie Tugend, Jean-marie FlamentAbstract:In this paper, we present a sedimentary and structural analysis that together with maps, sections and new Ar/Ar data enable to describe the tectono-sedimentary evolution of the Mauleon hyper-extended rift basin exposed in the W-Pyrenees. Hyper-extension processes that ultimately resulted in exhuming mantle rocks are the result of the subsequent development of two diachronous detachment systems related to two evolutional stages of rifting. An initial Late Aptian Early Albian crustal thinning phase is first recorded by the development of a crustal Necking Zone controlled by the north-vergent Southern Mauleon Detachment system. During a subsequent exhumation phase, active faulting migrates to the north with the emplacement of the Northern Mauleon detachment system that exhumed north section thinned continental crust and mantle rocks. This diachronous crustal thinning and exhumation processes are also recorded by the diachronous deposition of syn-tectonic sedimentary tracts above the two supra-detachment sub-basins. Syn-tectonic sedimentary tracts record the progressive exhumation of footwall rocks along detachment systems. Tectonic migration from the southern to the northern Mauleon Detachment system is recorded by the coeval deposition of “sag” deposits above the Necking Zone basin and of syn-tectonic tracts above exhumed rocks north section. Located on a hanging-wall situation related to the Mauleon hyper-extension structures, the Arzacq Basin also records a major crustal thinning phase as shown by its subsidence evolution so as by deep seismic images. The absence of major top-basement structures and its overall sag morphology suggest that crustal thinning processes occurred by decoupled extension of lower crustal levels contrasting with the Southern Mauleon Detachment system. Reconciling observations from the Mauleon and Arzacq Basins, we finally propose in this paper that they were the result of one and the same asymmetric crustal thinning and exhumation processes, where extension is accommodated into the upper crust in the Mauleon Basin (lower plate basin) and relayed in ductile lower crust below the Arzacq Basin (upper plate basin).
Emmanuel Masini - One of the best experts on this subject based on the ideXlab platform.
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The tectono-sedimentary evolution of a hyper-extended rift basin: the example of the Arzacq–Mauléon rift system (Western Pyrenees, SW France)
International Journal of Earth Sciences, 2014Co-Authors: Emmanuel Masini, Geoffroy Mohn, Gianreto Manatschal, Julie Tugend, Jean-marie FlamentAbstract:In this paper, we present a sedimentary and structural analysis that together with maps, sections and new Ar/Ar data enable to describe the tectono-sedimentary evolution of the Mauléon hyper-extended rift basin exposed in the W-Pyrenees. Hyper-extension processes that ultimately resulted in exhuming mantle rocks are the result of the subsequent development of two diachronous detachment systems related to two evolutional stages of rifting. An initial Late Aptian Early Albian crustal thinning phase is first recorded by the development of a crustal Necking Zone controlled by the north-vergent Southern Mauléon Detachment system. During a subsequent exhumation phase, active faulting migrates to the north with the emplacement of the Northern Mauléon detachment system that exhumed north section thinned continental crust and mantle rocks. This diachronous crustal thinning and exhumation processes are also recorded by the diachronous deposition of syn-tectonic sedimentary tracts above the two supra-detachment sub-basins. Syn-tectonic sedimentary tracts record the progressive exhumation of footwall rocks along detachment systems. Tectonic migration from the southern to the northern Mauléon Detachment system is recorded by the coeval deposition of “sag” deposits above the Necking Zone basin and of syn-tectonic tracts above exhumed rocks north section. Located on a hanging-wall situation related to the Mauléon hyper-extension structures, the Arzacq Basin also records a major crustal thinning phase as shown by its subsidence evolution so as by deep seismic images. The absence of major top-basement structures and its overall sag morphology suggest that crustal thinning processes occurred by decoupled extension of lower crustal levels contrasting with the Southern Mauléon Detachment system. Reconciling observations from the Mauléon and Arzacq Basins, we finally propose in this paper that they were the result of one and the same asymmetric crustal thinning and exhumation processes, where extension is accommodated into the upper crust in the Mauléon Basin (lower plate basin) and relayed in ductile lower crust below the Arzacq Basin (upper plate basin).
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the tectono sedimentary evolution of a hyper extended rift basin the example of the arzacq mauleon rift system western pyrenees sw france
International Journal of Earth Sciences, 2014Co-Authors: Emmanuel Masini, Geoffroy Mohn, Gianreto Manatschal, Julie Tugend, Jean-marie FlamentAbstract:In this paper, we present a sedimentary and structural analysis that together with maps, sections and new Ar/Ar data enable to describe the tectono-sedimentary evolution of the Mauleon hyper-extended rift basin exposed in the W-Pyrenees. Hyper-extension processes that ultimately resulted in exhuming mantle rocks are the result of the subsequent development of two diachronous detachment systems related to two evolutional stages of rifting. An initial Late Aptian Early Albian crustal thinning phase is first recorded by the development of a crustal Necking Zone controlled by the north-vergent Southern Mauleon Detachment system. During a subsequent exhumation phase, active faulting migrates to the north with the emplacement of the Northern Mauleon detachment system that exhumed north section thinned continental crust and mantle rocks. This diachronous crustal thinning and exhumation processes are also recorded by the diachronous deposition of syn-tectonic sedimentary tracts above the two supra-detachment sub-basins. Syn-tectonic sedimentary tracts record the progressive exhumation of footwall rocks along detachment systems. Tectonic migration from the southern to the northern Mauleon Detachment system is recorded by the coeval deposition of “sag” deposits above the Necking Zone basin and of syn-tectonic tracts above exhumed rocks north section. Located on a hanging-wall situation related to the Mauleon hyper-extension structures, the Arzacq Basin also records a major crustal thinning phase as shown by its subsidence evolution so as by deep seismic images. The absence of major top-basement structures and its overall sag morphology suggest that crustal thinning processes occurred by decoupled extension of lower crustal levels contrasting with the Southern Mauleon Detachment system. Reconciling observations from the Mauleon and Arzacq Basins, we finally propose in this paper that they were the result of one and the same asymmetric crustal thinning and exhumation processes, where extension is accommodated into the upper crust in the Mauleon Basin (lower plate basin) and relayed in ductile lower crust below the Arzacq Basin (upper plate basin).
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Necking of continental crust in magma‐poor rifted margins: Evidence from the fossil Alpine Tethys margins
Tectonics, 2012Co-Authors: Geoffroy Mohn, Gianreto Manatschal, Marco Beltrando, Emmanuel Masini, Nick KusznirAbstract:[1] Studies conducted in present-day magma-poor rifted margins reveal that the transition from weakly thinned continental crust (∼30 km) in proximal margins to hyper-extended crust (≤10 km) in distal margins occurs within a narrow Zone, referred to as the Necking Zone. We have identified relics of a Necking Zone and of the adjacent distal margin in the Campo, Grosina and Bernina units of the fossil Alpine Tethys margins and investigated the deformation and sedimentary processes associated with extreme crustal thinning during rifting. Within the basement rocks of the Necking Zone, we show that: (1) Grosina basement represents pre-rift upper/middle crust, while the underlying Campo unit consists of pre-rift middle/lower crust that was exhumed and cooled below ∼300°C by ca. 180 Ma, when rifting started to localize within the future distal margin; (2) the juxtaposition of the Campo and Grosina units was accommodated by the Eita shear Zone, which is interpreted as a decollement/decoupling horizon active at mid-crustal depth at 180–205 Ma; (3) the Grosina unit hosts a large-scale brittle detachment fault. Our observations suggest that crustal thinning, accommodated through the Necking Zone, is the result of the interplay between detachment faulting in the brittle layers and decoupling and thinning in ductile quartzo-feldspatic middle crustal levels along localized ductile decollements. The excision of ductile mid-crustal layers and the progressive embrittlement of the crust enables major detachment faults to cut into the underlying mantle, exhuming it to the seafloor. This structural evolution can explain the first-order crustal architecture of many present-day rifted margins.
Gianreto Manatschal - One of the best experts on this subject based on the ideXlab platform.
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Geophysical fingerprints of hyper-extended, exhumed and embryonic oceanic domains: the example from the Iberia–Newfoundland rifted margins
Marine Geophysical Research, 2016Co-Authors: Natasha Stanton, Gianreto Manatschal, Julia Autin, Daniel Sauter, Marcia Maia, Adriano VianaAbstract:This study investigates the magnetic and gravity signatures and associated seismic character of hyper-extended, exhumed and embryonic oceanic domains along the conjugate Iberia–Newfoundland rifted margins. As these margins have been drilled down to basement along their distal parts, it is possible to explore and test different geophysical techniques and interpretations. The aims of this work are twofold: (1) to investigate the location and nature of the two main marginal boundaries—the Necking Zone and the J Anomaly, which define the limits of major domains; and (2) to map the lateral variations of gravity and magnetic signatures and their detailed correlation with seismic data, from the proximal margin until the first unequivocal oceanic magnetic anomaly (e.g. C34 Anomaly). The results point out that the J Anomaly corresponds to a first-order tectono-magmatic boundary, with a basement formed by polyphase magmatism. It marks the boundary between the exhumed mantle domain, with little magmatic additions, from a domain oceanwards that reveals comparable trends, frequencies and a general magnetic pattern at both sides of the Atlantic, suggesting a coeval evolution. We propose that the domain between the J and the C34 Anomalies was formed by an embryonic spreading system, with intermittent budgets of magma, similar to those observed at very slow spreading systems. The J Anomaly may thus correspond to the location of lithospheric breakup though its origin and the nature of the domain oceanwards remains to be constrained.
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The role of inheritance in structuring hyperextended rift systems: Some considerations based on observations and numerical modeling
Gondwana Research, 2015Co-Authors: Gianreto Manatschal, L.l. Lavier, Pauline CheninAbstract:A long-standing question in Earth Sciences is related to the importance of inheritance in controlling tectonic processes. In contrast to physical processes that are generally applicable, assessing the role of inheritance suffers from two major problems: firstly, it is difficult to appraise without having insights into the history of a geological system; and secondly all inherited features are not reactivated during subsequent deformation phases. Therefore, the aim of this paper is to give some conceptual framework about how inheritance may control the architecture and evolution of hyperextended rift systems. In this paper, we use the term inheritance to refer to the difference between an “ideal” layer-cake type lithosphere and a “real” lithosphere containing heterogeneities. The underlying philosophy of this work is that the evolution of hyperextended rift systems reflects the interplay between their inheritance (innate/“genetic code”) and the physical processes at play (acquired/external factors). Thus, by observing the architecture and evolution of hyperextended rift systems and integrating the physical processes, one may get hints on what may have been the original inheritance of a system. We first define 3 types of inheritance, namely structural, compositional and thermal inheritance and develop a simple and robust terminology able to describe and link observations made at different scales using geological, geophysical and modeling approaches. To this, we add a definition of rift-induced processes, i.e. processes leading to compositional changes during rifting (e.g. serpentinization or decompression melting). Using this approach, we focus on 3 well-studied rift systems that are the Alpine Tethys, Pyrenean–Bay of Biscay and Iberia–Newfoundland rift systems. However, as all these examples are magma-poor, hyperextended rift systems that evolved over a Variscan lithosphere the concepts developed in this paper cannot be applied universally. For the studied examples we can show that: 1) the inherited structures did not significantly control the location of breakup 2) the inherited thermal state may control the mode and architecture of rift systems, in particular the architecture of the Necking Zone 3) the architecture of the Necking Zone may be influenced by the distribution and importance of ductile layers during decoupled deformation and is consequently controlled by the thermal structure and/or the inherited composition of the crust 4) conversely, the deformation in hyperextended domains is strongly controlled by weak hydrated minerals (e.g. clay, serpentinite) that result from the breakdown of feldspar and olivine due to fluid and reaction assisted deformation 5) inherited structures, in particular weaknesses, are important in controlling strain localization on a local scale and during early stages of rifting 6) inherited mantle composition and rift-related mantle processes may control the rheology of the mantle, the magmatic budget, the thermal structure and the localization of final rifting. These key observations show that both inheritance and rift-induced processes played a significant role in the development of the magma-poor southern North Atlantic and Alpine Tethys rift systems and that the role of inheritance may change as the physical conditions vary during the evolving rifting and as rift-induced processes (serpentinization; magma) become more important. Thus, it is not only important to determine the “genetic code” of a rift system, but also to understand how it interacts and evolves during rifting. Understanding how far these new ideas and concepts derived from the well-studied hyperextended rift systems of the southern North Atlantic and Alpine Tethys can be translated to other less explored hyperextended rift systems will be one of the challenges of future research in rifted margins.
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The tectono-sedimentary evolution of a hyper-extended rift basin: the example of the Arzacq–Mauléon rift system (Western Pyrenees, SW France)
International Journal of Earth Sciences, 2014Co-Authors: Emmanuel Masini, Geoffroy Mohn, Gianreto Manatschal, Julie Tugend, Jean-marie FlamentAbstract:In this paper, we present a sedimentary and structural analysis that together with maps, sections and new Ar/Ar data enable to describe the tectono-sedimentary evolution of the Mauléon hyper-extended rift basin exposed in the W-Pyrenees. Hyper-extension processes that ultimately resulted in exhuming mantle rocks are the result of the subsequent development of two diachronous detachment systems related to two evolutional stages of rifting. An initial Late Aptian Early Albian crustal thinning phase is first recorded by the development of a crustal Necking Zone controlled by the north-vergent Southern Mauléon Detachment system. During a subsequent exhumation phase, active faulting migrates to the north with the emplacement of the Northern Mauléon detachment system that exhumed north section thinned continental crust and mantle rocks. This diachronous crustal thinning and exhumation processes are also recorded by the diachronous deposition of syn-tectonic sedimentary tracts above the two supra-detachment sub-basins. Syn-tectonic sedimentary tracts record the progressive exhumation of footwall rocks along detachment systems. Tectonic migration from the southern to the northern Mauléon Detachment system is recorded by the coeval deposition of “sag” deposits above the Necking Zone basin and of syn-tectonic tracts above exhumed rocks north section. Located on a hanging-wall situation related to the Mauléon hyper-extension structures, the Arzacq Basin also records a major crustal thinning phase as shown by its subsidence evolution so as by deep seismic images. The absence of major top-basement structures and its overall sag morphology suggest that crustal thinning processes occurred by decoupled extension of lower crustal levels contrasting with the Southern Mauléon Detachment system. Reconciling observations from the Mauléon and Arzacq Basins, we finally propose in this paper that they were the result of one and the same asymmetric crustal thinning and exhumation processes, where extension is accommodated into the upper crust in the Mauléon Basin (lower plate basin) and relayed in ductile lower crust below the Arzacq Basin (upper plate basin).
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the tectono sedimentary evolution of a hyper extended rift basin the example of the arzacq mauleon rift system western pyrenees sw france
International Journal of Earth Sciences, 2014Co-Authors: Emmanuel Masini, Geoffroy Mohn, Gianreto Manatschal, Julie Tugend, Jean-marie FlamentAbstract:In this paper, we present a sedimentary and structural analysis that together with maps, sections and new Ar/Ar data enable to describe the tectono-sedimentary evolution of the Mauleon hyper-extended rift basin exposed in the W-Pyrenees. Hyper-extension processes that ultimately resulted in exhuming mantle rocks are the result of the subsequent development of two diachronous detachment systems related to two evolutional stages of rifting. An initial Late Aptian Early Albian crustal thinning phase is first recorded by the development of a crustal Necking Zone controlled by the north-vergent Southern Mauleon Detachment system. During a subsequent exhumation phase, active faulting migrates to the north with the emplacement of the Northern Mauleon detachment system that exhumed north section thinned continental crust and mantle rocks. This diachronous crustal thinning and exhumation processes are also recorded by the diachronous deposition of syn-tectonic sedimentary tracts above the two supra-detachment sub-basins. Syn-tectonic sedimentary tracts record the progressive exhumation of footwall rocks along detachment systems. Tectonic migration from the southern to the northern Mauleon Detachment system is recorded by the coeval deposition of “sag” deposits above the Necking Zone basin and of syn-tectonic tracts above exhumed rocks north section. Located on a hanging-wall situation related to the Mauleon hyper-extension structures, the Arzacq Basin also records a major crustal thinning phase as shown by its subsidence evolution so as by deep seismic images. The absence of major top-basement structures and its overall sag morphology suggest that crustal thinning processes occurred by decoupled extension of lower crustal levels contrasting with the Southern Mauleon Detachment system. Reconciling observations from the Mauleon and Arzacq Basins, we finally propose in this paper that they were the result of one and the same asymmetric crustal thinning and exhumation processes, where extension is accommodated into the upper crust in the Mauleon Basin (lower plate basin) and relayed in ductile lower crust below the Arzacq Basin (upper plate basin).
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Necking of continental crust in magma‐poor rifted margins: Evidence from the fossil Alpine Tethys margins
Tectonics, 2012Co-Authors: Geoffroy Mohn, Gianreto Manatschal, Marco Beltrando, Emmanuel Masini, Nick KusznirAbstract:[1] Studies conducted in present-day magma-poor rifted margins reveal that the transition from weakly thinned continental crust (∼30 km) in proximal margins to hyper-extended crust (≤10 km) in distal margins occurs within a narrow Zone, referred to as the Necking Zone. We have identified relics of a Necking Zone and of the adjacent distal margin in the Campo, Grosina and Bernina units of the fossil Alpine Tethys margins and investigated the deformation and sedimentary processes associated with extreme crustal thinning during rifting. Within the basement rocks of the Necking Zone, we show that: (1) Grosina basement represents pre-rift upper/middle crust, while the underlying Campo unit consists of pre-rift middle/lower crust that was exhumed and cooled below ∼300°C by ca. 180 Ma, when rifting started to localize within the future distal margin; (2) the juxtaposition of the Campo and Grosina units was accommodated by the Eita shear Zone, which is interpreted as a decollement/decoupling horizon active at mid-crustal depth at 180–205 Ma; (3) the Grosina unit hosts a large-scale brittle detachment fault. Our observations suggest that crustal thinning, accommodated through the Necking Zone, is the result of the interplay between detachment faulting in the brittle layers and decoupling and thinning in ductile quartzo-feldspatic middle crustal levels along localized ductile decollements. The excision of ductile mid-crustal layers and the progressive embrittlement of the crust enables major detachment faults to cut into the underlying mantle, exhuming it to the seafloor. This structural evolution can explain the first-order crustal architecture of many present-day rifted margins.
Julie Tugend - One of the best experts on this subject based on the ideXlab platform.
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The tectono-sedimentary evolution of a hyper-extended rift basin: the example of the Arzacq–Mauléon rift system (Western Pyrenees, SW France)
International Journal of Earth Sciences, 2014Co-Authors: Emmanuel Masini, Geoffroy Mohn, Gianreto Manatschal, Julie Tugend, Jean-marie FlamentAbstract:In this paper, we present a sedimentary and structural analysis that together with maps, sections and new Ar/Ar data enable to describe the tectono-sedimentary evolution of the Mauléon hyper-extended rift basin exposed in the W-Pyrenees. Hyper-extension processes that ultimately resulted in exhuming mantle rocks are the result of the subsequent development of two diachronous detachment systems related to two evolutional stages of rifting. An initial Late Aptian Early Albian crustal thinning phase is first recorded by the development of a crustal Necking Zone controlled by the north-vergent Southern Mauléon Detachment system. During a subsequent exhumation phase, active faulting migrates to the north with the emplacement of the Northern Mauléon detachment system that exhumed north section thinned continental crust and mantle rocks. This diachronous crustal thinning and exhumation processes are also recorded by the diachronous deposition of syn-tectonic sedimentary tracts above the two supra-detachment sub-basins. Syn-tectonic sedimentary tracts record the progressive exhumation of footwall rocks along detachment systems. Tectonic migration from the southern to the northern Mauléon Detachment system is recorded by the coeval deposition of “sag” deposits above the Necking Zone basin and of syn-tectonic tracts above exhumed rocks north section. Located on a hanging-wall situation related to the Mauléon hyper-extension structures, the Arzacq Basin also records a major crustal thinning phase as shown by its subsidence evolution so as by deep seismic images. The absence of major top-basement structures and its overall sag morphology suggest that crustal thinning processes occurred by decoupled extension of lower crustal levels contrasting with the Southern Mauléon Detachment system. Reconciling observations from the Mauléon and Arzacq Basins, we finally propose in this paper that they were the result of one and the same asymmetric crustal thinning and exhumation processes, where extension is accommodated into the upper crust in the Mauléon Basin (lower plate basin) and relayed in ductile lower crust below the Arzacq Basin (upper plate basin).
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the tectono sedimentary evolution of a hyper extended rift basin the example of the arzacq mauleon rift system western pyrenees sw france
International Journal of Earth Sciences, 2014Co-Authors: Emmanuel Masini, Geoffroy Mohn, Gianreto Manatschal, Julie Tugend, Jean-marie FlamentAbstract:In this paper, we present a sedimentary and structural analysis that together with maps, sections and new Ar/Ar data enable to describe the tectono-sedimentary evolution of the Mauleon hyper-extended rift basin exposed in the W-Pyrenees. Hyper-extension processes that ultimately resulted in exhuming mantle rocks are the result of the subsequent development of two diachronous detachment systems related to two evolutional stages of rifting. An initial Late Aptian Early Albian crustal thinning phase is first recorded by the development of a crustal Necking Zone controlled by the north-vergent Southern Mauleon Detachment system. During a subsequent exhumation phase, active faulting migrates to the north with the emplacement of the Northern Mauleon detachment system that exhumed north section thinned continental crust and mantle rocks. This diachronous crustal thinning and exhumation processes are also recorded by the diachronous deposition of syn-tectonic sedimentary tracts above the two supra-detachment sub-basins. Syn-tectonic sedimentary tracts record the progressive exhumation of footwall rocks along detachment systems. Tectonic migration from the southern to the northern Mauleon Detachment system is recorded by the coeval deposition of “sag” deposits above the Necking Zone basin and of syn-tectonic tracts above exhumed rocks north section. Located on a hanging-wall situation related to the Mauleon hyper-extension structures, the Arzacq Basin also records a major crustal thinning phase as shown by its subsidence evolution so as by deep seismic images. The absence of major top-basement structures and its overall sag morphology suggest that crustal thinning processes occurred by decoupled extension of lower crustal levels contrasting with the Southern Mauleon Detachment system. Reconciling observations from the Mauleon and Arzacq Basins, we finally propose in this paper that they were the result of one and the same asymmetric crustal thinning and exhumation processes, where extension is accommodated into the upper crust in the Mauleon Basin (lower plate basin) and relayed in ductile lower crust below the Arzacq Basin (upper plate basin).
Geoffroy Mohn - One of the best experts on this subject based on the ideXlab platform.
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The tectono-sedimentary evolution of a hyper-extended rift basin: the example of the Arzacq–Mauléon rift system (Western Pyrenees, SW France)
International Journal of Earth Sciences, 2014Co-Authors: Emmanuel Masini, Geoffroy Mohn, Gianreto Manatschal, Julie Tugend, Jean-marie FlamentAbstract:In this paper, we present a sedimentary and structural analysis that together with maps, sections and new Ar/Ar data enable to describe the tectono-sedimentary evolution of the Mauléon hyper-extended rift basin exposed in the W-Pyrenees. Hyper-extension processes that ultimately resulted in exhuming mantle rocks are the result of the subsequent development of two diachronous detachment systems related to two evolutional stages of rifting. An initial Late Aptian Early Albian crustal thinning phase is first recorded by the development of a crustal Necking Zone controlled by the north-vergent Southern Mauléon Detachment system. During a subsequent exhumation phase, active faulting migrates to the north with the emplacement of the Northern Mauléon detachment system that exhumed north section thinned continental crust and mantle rocks. This diachronous crustal thinning and exhumation processes are also recorded by the diachronous deposition of syn-tectonic sedimentary tracts above the two supra-detachment sub-basins. Syn-tectonic sedimentary tracts record the progressive exhumation of footwall rocks along detachment systems. Tectonic migration from the southern to the northern Mauléon Detachment system is recorded by the coeval deposition of “sag” deposits above the Necking Zone basin and of syn-tectonic tracts above exhumed rocks north section. Located on a hanging-wall situation related to the Mauléon hyper-extension structures, the Arzacq Basin also records a major crustal thinning phase as shown by its subsidence evolution so as by deep seismic images. The absence of major top-basement structures and its overall sag morphology suggest that crustal thinning processes occurred by decoupled extension of lower crustal levels contrasting with the Southern Mauléon Detachment system. Reconciling observations from the Mauléon and Arzacq Basins, we finally propose in this paper that they were the result of one and the same asymmetric crustal thinning and exhumation processes, where extension is accommodated into the upper crust in the Mauléon Basin (lower plate basin) and relayed in ductile lower crust below the Arzacq Basin (upper plate basin).
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the tectono sedimentary evolution of a hyper extended rift basin the example of the arzacq mauleon rift system western pyrenees sw france
International Journal of Earth Sciences, 2014Co-Authors: Emmanuel Masini, Geoffroy Mohn, Gianreto Manatschal, Julie Tugend, Jean-marie FlamentAbstract:In this paper, we present a sedimentary and structural analysis that together with maps, sections and new Ar/Ar data enable to describe the tectono-sedimentary evolution of the Mauleon hyper-extended rift basin exposed in the W-Pyrenees. Hyper-extension processes that ultimately resulted in exhuming mantle rocks are the result of the subsequent development of two diachronous detachment systems related to two evolutional stages of rifting. An initial Late Aptian Early Albian crustal thinning phase is first recorded by the development of a crustal Necking Zone controlled by the north-vergent Southern Mauleon Detachment system. During a subsequent exhumation phase, active faulting migrates to the north with the emplacement of the Northern Mauleon detachment system that exhumed north section thinned continental crust and mantle rocks. This diachronous crustal thinning and exhumation processes are also recorded by the diachronous deposition of syn-tectonic sedimentary tracts above the two supra-detachment sub-basins. Syn-tectonic sedimentary tracts record the progressive exhumation of footwall rocks along detachment systems. Tectonic migration from the southern to the northern Mauleon Detachment system is recorded by the coeval deposition of “sag” deposits above the Necking Zone basin and of syn-tectonic tracts above exhumed rocks north section. Located on a hanging-wall situation related to the Mauleon hyper-extension structures, the Arzacq Basin also records a major crustal thinning phase as shown by its subsidence evolution so as by deep seismic images. The absence of major top-basement structures and its overall sag morphology suggest that crustal thinning processes occurred by decoupled extension of lower crustal levels contrasting with the Southern Mauleon Detachment system. Reconciling observations from the Mauleon and Arzacq Basins, we finally propose in this paper that they were the result of one and the same asymmetric crustal thinning and exhumation processes, where extension is accommodated into the upper crust in the Mauleon Basin (lower plate basin) and relayed in ductile lower crust below the Arzacq Basin (upper plate basin).
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Necking of continental crust in magma‐poor rifted margins: Evidence from the fossil Alpine Tethys margins
Tectonics, 2012Co-Authors: Geoffroy Mohn, Gianreto Manatschal, Marco Beltrando, Emmanuel Masini, Nick KusznirAbstract:[1] Studies conducted in present-day magma-poor rifted margins reveal that the transition from weakly thinned continental crust (∼30 km) in proximal margins to hyper-extended crust (≤10 km) in distal margins occurs within a narrow Zone, referred to as the Necking Zone. We have identified relics of a Necking Zone and of the adjacent distal margin in the Campo, Grosina and Bernina units of the fossil Alpine Tethys margins and investigated the deformation and sedimentary processes associated with extreme crustal thinning during rifting. Within the basement rocks of the Necking Zone, we show that: (1) Grosina basement represents pre-rift upper/middle crust, while the underlying Campo unit consists of pre-rift middle/lower crust that was exhumed and cooled below ∼300°C by ca. 180 Ma, when rifting started to localize within the future distal margin; (2) the juxtaposition of the Campo and Grosina units was accommodated by the Eita shear Zone, which is interpreted as a decollement/decoupling horizon active at mid-crustal depth at 180–205 Ma; (3) the Grosina unit hosts a large-scale brittle detachment fault. Our observations suggest that crustal thinning, accommodated through the Necking Zone, is the result of the interplay between detachment faulting in the brittle layers and decoupling and thinning in ductile quartzo-feldspatic middle crustal levels along localized ductile decollements. The excision of ductile mid-crustal layers and the progressive embrittlement of the crust enables major detachment faults to cut into the underlying mantle, exhuming it to the seafloor. This structural evolution can explain the first-order crustal architecture of many present-day rifted margins.
